The object of this project is to understand the physiological role of enkephalins in brain. Enkephalins were found to be unevenly distributed in the brain with the highest concentrations in globus pallidus and caudate and lowest in hippocampus and cortex. Furthermore, it was demonstrated that cell bodies of striatal enkephalin may be located in neostriatum or globus pallidus. Chronic treatments with haloperidol, led to a marked increase in striatal enkephalin content suggesting the possible involvement of striatal enkephalinergic neurons in the action of this antischizophrenic drug. BIBLIOGRAPHIC REFERENCES: Yang, H.-Y.T., Hong, J.S. and Costa, E.: Regional distribution of leu- and met-enkephalin in rat brain. Neuropharmacology 16: 303-397, 1977.